example refactor snowflake module system

nix/snow/flake/modules/nixosModules.nix

@@ -0,0 +1,26 @@
+{ self, lib, moduleLocation, ... }:
+let
+  inherit (lib)
+    mapAttrs
+    mkOption
+    types
+    ;
+in
+{
+  options = {
+    flake.nixosModules = mkOption {
+      type = types.lazyAttrsOf types.deferredModule;
+      default = { };
+      apply = mapAttrs (k: v: {
+        _class = "nixos";
+        _file = "${toString moduleLocation}#nixosModules.${k}";
+        imports = [ v ];
+      });
+      description = ''
+        NixOS modules.
+
+        You may use this for reusable pieces of configuration, service modules, etc.
+      '';
+    };
+  };
+}